Expand

The Expand module allows a Model's property to be filled with connected data - read from the same or another Database. In SQL this could be achieved with JOINs.

Simple Expand

An Expand statement can be described as follows:

• Document(s) are retrieved from a Database.
• Expand (the keyword $expand)
• the property (property)
• with the Document
• from Database (database)
• where the foreign property (foreign)
• matches the value of the local property (property).

Below are some example query strings utilizing the Expand module

Expand a single property

Schema:

$expand=property/database/foreign

Example:

$expand=person/contacts/email

Expand more than one properties

Schema:

$expand=property1/database1/foreign1/-/property2/database2/foreign2

Example:

$expand=person/contacts/email/-/book/book/isbn_10

Expand a filtered set

Schema:

filter-property=filter-value&$expand=property/database/foreign

$expand=property/database/foreign&filter-property=filter-value

Example:

title=The Hobbit&$expand=person/contacts/email

$expand=person/contacts/email&title=The Hobbit

More about filtering.

Expand as

It is possible to define a different property to be filled with the expanded Document(s). This prevents the original property from being overwritten.

Such Expand statements are slightly different:

• Document(s) are retrieved from a Database.
• Expand (the keyword $expand)
• the Document(s)
• with the Document
• from Database (database)
• where the foreign property (foreign)
• matches the value of the local property (property)
• as property key as.

Schema:

$expand=property/database/foreign/as

Example:

$expand=person/contacts/email/contact

Expand to many

Per default Documents are only resolved as a one-to-one relationship. To avoid cases where a Document has a collection of expanded Documents and others have a single connected Document, one-to-many relationships have to be configured explicitly. This is achieved through adding an asterisk ("*") to the local property key.

Schema:

$expand=property*/database/foreign

$expand=property*/database/foreign/as

Example:

$expand=person*/contacts/email

$expand=person*/contacts/email/contact